The portable chest x-ray (CXR) is one of the most commonly requested diagnostic medical tests performed in hospitals throughout the world. Portable CXRs are performed nearly daily on some of the sickest patients in hospitals, including those with pleural effusions, support lines and tubes. Thus, patients who require CXRs the most, are in the intensive care unit of the hospital.
A portable CXR is obtained typically at a patient's hospital bed when the patient is too sick to travel to the radiology department for an optimal upright posterior-anterior (PA) and lateral CXR or upright abdomen. Upright images more effectively evaluate effusions, e.g., as fluid settles due to gravity. Conversely, any trapped air rises and when found together in the same cavity with fluid, (e.g., such as in hydropneumothorax, abscess or empyema), an air-fluid level (for example) can be detected. Air collections (i.e., collections of trapped air) alone can also be realized in erect projections. If one does not know the degree of upright projection, however, one cannot rule out the presence of air. Additionally, abdomen portable projections are often obtained in decubitus positions. In this position the patient is placed on their side to make use of gravity and perpendicular x-ray beams to demonstrate free air, or air fluid levels.
The portable CXR is usually not imaged at a fully upright position because the x-ray source would have to be placed nearly in the patients lap in order to achieve a fully upright position and thus obtain a similar erect orientation as would be obtained in a radiology department. Instead, most CXRs are obtained at 45 degrees or less, often due to patient condition, or a technologist style/training. Accordingly, many portable CXRs are obtained at 45 degrees or less (though the exact angle is unknown to the medical community, due to the lack of a device to measure such an angle), often due to the patient's condition, or the style or training of the technologist or technician operating the CXR.
For this reason, portable radiography, such as CXRs, has been well documented as often being inconsistent, inaccurate and inadequate due to the inability to consistently and repetitively place the patient at a specific angle in relation to gravity. As stated above, in order for a radiologist to achieve an optimal quality of interpretation, the technologist must attempt to position a patient in the most upright position. In reality, however, the patient's position must also be balanced with his or her condition and their ability to achieve this nearly upright position. Positioning the patient in the most upright position provides for the best evaluation of effusions, rules out the presence of free air, and/or allows for a more accurate detection of air-fluid levels. Optimally, the images are obtained at similar angles each day to allow for accurate comparisons between each consecutive day.
Unfortunately, there are many instances where clinicians will order a CT (Computed Tomography) to differentiate effusion from consolidation (infection such as pneumonia), or to simply compare effusions since upright angulation is rarely truly known due to complications in angulation consistency. Thus, the patient is exposed to about 100 times more radiation; hundreds of dollars of increased expenditures for the more expensive technology and dangerous patient transport to the radiology department.
FIGS. 7A, B illustrate a comparison of a patient in an upright position and in a nearly supine position (lying down) taken by CXRs on different days. This comparison shows the change in opacification (representing effusion) depending on cassette (and hence a patient) angle. FIG. 7A shows an upright CXR demonstrating a left pleural effusion. The up arrow, used in conventional x-ray images, indicates an upright projection to the radiologist. However, there is no rule as to how “upright” the patient is among technologists; rather, this is a subjective decision based on the technologists choice and how busy they are. Additionally, there is no current method to evaluate technologist performance. FIG. 7B is more supine and shows the effusion distributed as a hazy ill-defined opacity over the lower left hemithorax (i.e., the left side of the chest).
Not knowing the degree of angulation in which each CXR is taken makes objective comparison of the amount of effusion impossible in most cases. For example, the right hand image can falsely indicate improvement of effusion. However, the next day (not shown here) could demonstrate an image similar to FIG. 7B (i.e., showing no effusion). Conversely, the two exams could falsely represent changing consolidation rather than effusion itself, leading clinicians to believe there is a worsening infection. Of note, effusions often mask or mimic consolidations (x-ray indicators of pneumonia). Misunderstanding of physiological process of portable x-ray exams, enhanced by an unknown patient angulation; too often leads to unnecessary use of CT (higher radiation and cost), as noted above.
Additionally, effusions often indicate the severity of a patient's condition and at times require drainage. Accordingly, increasing effusion over time is one indicator of the need for immediate thoracentesis (drainage of developing effusion). Thus, accurately quantifying or identifying the presence of an effusion, through use of an angulation measurement is highly necessary and at times a matter of life or death.
As also can be seen by FIGS. 7A, B there are currently no adequate quantitative markers on conventional x-ray images that indicate the degree/angle at which the x-ray image was taken. That is, conventional x-ray images only differentiate between supine and non-supine positions (i.e., upright and lying down).
Thus, there is a need for a device and method for more accurately quantifying the angulation at which an x-ray, for example, a CXR is taken. It would be particularly desirable to provide such a device and method that would allow the radiologist or providing physician to determine the degree of angulation by a glance as well as having left and right markers for every x-ray. Such devices preferably would be simple in construction and less costly than prior art devices.